At the present time the typical vehicle seat belt extends in a substantially vertical run from an outside anchorage fixed to the vehicle floor on one side of the vehicle seat to a door post anchorage which defines a belt redirection or deflection point above the vehicle seat. The belt is slidably redirected by the door post anchorage into a diagonal run constituting a shoulder belt portion. The diagonal run extends to a buckle which is adapted for detachable connection to an inside anchorage fixed to the vehicle floor on the other side of the vehicle seat.
The outside anchorage is typically an inertia retractor which winds up the excess seat belt on a spool when the belt is not in use. A seat occupant can pull or pay out some of the excess seat belt to buckle it in position across his body The retractor allows relatively slow movements by the occupant, such as leaning forward to reach into a glove compartment, but the retractor reacts to sudden vehicles deceleration to grip the belt and prevent it from being pulled out relatively rapidly. This prevents the user from being thrown forward in a vehicle accident. The seatbelt usually also incorporates a lap run which constitutes a continuation of the shoulder belt or diagonal run, with the buckle slidably redirecting the diagonal run across the lap to define the lap run. The lap run is secured to a lap belt anchorage which is fixed to the vehicle floor adjacent the retractor anchorage.
The locations of the door post and seat buckle anchorages are reasonably effective to properly locate the diagonal run across the chest of most adults, but totally ineffective in the case of a smaller seat occupant such as a child. The diagonal run usually passes directly across the neck or face of a child. Furthermore, the normal operation of the seatbelt retractor undesirably allows a child to pull out some belt slack and wriggle out of the restraint of the seatbelt.
A considerable number of devices have been proposed in the prior art to enable relocation of the diagonal run of the seatbelt so that it will pass across the chest of small seat occupants. However, all of the devices known to applicant depend for operation upon modifying the construction and location of the conventional door post anchorage. Some include a track integrally fixed to the door post and mounting a vertically movable traveler. The traveler slidably accepts the seatbelt in the same way as a conventional door post anchorage, but it can be moved downwardly to a new position, and retightened in that position, to lower the belt redirection or deflection point. U.S. Pats. Nos. 4,640,550 (Hakansson), 4,652,012 (Biller et al), 4,470,618 (Ono), and 4,573,708 (Vrorsson) disclose devices of this general type. Such devices require such significant modification to existing door post anchorages that retrofitting them to already manufactured vehicles is not practical. Furthermore, such devices are incapable of selectively disabling the usual seatbelt retractor/pay-out devices. Consequently, small children can circumvent their purpose and escape the restraint of the seatbelt.